The Ministry of Defence invited media in September last year to attend the farewell of the last contingent of NZ Defence Force personnel, when it left for a six-month deployment to Afghanistan.

The invitation was headed "Last contingent departs for Afghanistan", which seemed to affirm a major decision the Government had announced a few weeks earlier - the "sensible, orderly and professional" early withdrawal of troops.

We have had troops in Afghanistan since late 2001, contributing to the "war on terror". Under the withdrawal plan, the New Zealand Provincial Reconstruction Team would be back from Bamiyan by the end of April, leaving the local forces to it.

This, presumably, was preferable to an earlier plan to withdraw our troops by September 2014. Prime Minister John Key explained it, saying the Government had been encouraged by the International Security Assistance Force to bring the withdrawal date forward. The rebuilding of Bamiyan airport (we were told) was a consideration, too: this would make it off-limits to our Hercules aircraft after April.

But room for manoeuvre could be found in the fine print. Future support was likely to include sending a small number of Defence Force trainers to the Afghanistan National Army Officer Training Academy later in 2013.

Sure enough, this week we learned the Cabinet has approved a contingent of 27 military personnel, including three SAS soldiers, staying on for a year. Mr Key said this "small niche" contribution would remain, mainly in Kabul, to work with other international forces.

Labour claims the Government has broken a promise. Its defence spokesman, Iain Lees-Galloway, said the deployment was a new mission in a new area with a new mandate that extended New Zealand's commitment indefinitely.

Mr Key denies this. But he obviously dipped deep into his spin doctor's bag of creative verse to describe it as "a legacy commitment". It seems New Zealand must stay on to honour the commitment made to Afghanistan, including the deaths of 10 Defence Force personnel.

Perhaps not enough attention was paid to those commitments when Mr Key was discussing the withdrawal.

If we honour the casualties of war by staying on, shouldn't we still be ensconced in Gallipoli, Crete, Vietnam and many other theatres of war?